// Copyright 2024 The DMBMX2Tools Authors
// SPDX-License-Identifier: MIT

#pragma once
#include <base/Types.hpp>
#include <vector>

namespace dmtools::io {

	enum class StreamSeekDirection : u8 {
		Beg,
		Cur,
		End
	};

	using StreamDiff = i64;

	// TODO: Communicate error conditions using ErrorOr<> instead of
	// -1 values.

	/// A abstract stream of bytes. We use a custom implementation
	/// instead of C++ IO streams mostly for control reasons, and 
	/// also to avoid exceptions (we'll use ErrorOr for errors later on)
	struct Stream {
		Stream() = default;
		virtual ~Stream() = default;

		Stream(const Stream&) = delete;
		Stream(Stream&&) = delete;

		virtual void Flush() { return; }

		virtual StreamDiff ReadSome(u8* buffer, usize length) = 0;

		StreamDiff ReadSome(std::vector<u8>& buffer);

		virtual StreamDiff WriteSome(const u8* buffer, usize length) {
			// Default implementation disallows writes. Can be changed
			return -1;
		}

		StreamDiff WriteSome(const std::vector<u8>& buffer);

		/// Reads a single POD type from stream
		template <class T>
		inline bool ReadObject(T& obj) {
			auto sz = ReadSome(std::bit_cast<u8*>(&obj), sizeof(T));
			if(sz != sizeof(T))
				return false;
			return true;
		}

		template <class T>
		inline bool WriteObject(const T& obj) {
			auto sz = WriteSome(std::bit_cast<const u8*>(&obj), sizeof(T));
			if(sz != sizeof(T))
				return false;
			return true;
		}

		virtual StreamDiff Seek(StreamDiff where, StreamSeekDirection dir) = 0;

		virtual StreamDiff Tell() const = 0;

		virtual bool Ok() const = 0;

		virtual bool Eof() const = 0;

		inline operator bool() const {
			return Ok() && !Eof();
		}
	};

} // namespace dmtools